Combustion apparatus and method



Sept. 5, 1944. H. J. KERR 'mA-AL coMBUsToN APPARATUS AND METHOD 'Filed Ilarch '7, 1941 8 SheelzsfSheeil 1 INVENTORJ Illlllllllll l |||l Il H. J.v KERR ErYAL coMBUsTIoN `APPARA'LUS AAND METHOD Filed March 7, 1941 8 Sheets-Sheet 2 A roRNEY.

Sept. 5, 1944-. H. J. KERR ErAL coMBusTIoN APPARATUS AND METHOD 8 Sheets-Sheet 3 Filed March 7. 1941 .Pw/ooo l oo ATTORNEY.

Sept.5,1944, H, J. KERR Em. v2,357,303

COMBUSTION APPARATUS AND METHOD Filed March '7. 1941 8 Sheets-Sheet 4 rzg. 7

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COMBU'STIO-N APPAATUS AND METHOD Filed March 7, 1941 8 sheets-sheet 5 Fig; I0

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Sept. 5, 1944. H. J. KERR ETAL COMBUSTION APPARATUS AND METHOD Y 8 Sheets-Sheet 6 Filed March 7, 1941 LlmiLlx Howard J ken', .Jb/nes Hefe/9er, BY @far e/ Waffs l Sept. 5, 1 944. H. J. KERR ETAL COMBUSTION APPARATUS AND METHOD Filed March 7, 1941 8 Sheets-.Sheet 7 INVENTORSl Sept. 5, 1944.

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'H1 J. KERR Erm.. 2,357,303

COMBUSTION APPARATUS AND METHOD Filed March '7. 1941 8 Sheets-Sheet S INV EM ORS Howard J Ken; James F/e c/fer',

Patented Sept. 5, 1944 COMUSTION APPARATUS AND METHOD Howard J. Kerr. Westfield, N. E., and James Fletcher. Akron. George A. Watts. Barherton, and Lambert Kooistra, Akron, Ghia, assignors to The Babcock s Wilcox Company, Newark, N. Si.. a corporation oi New .Jersey1 Application March '1, i641, serial No. 382,264

21 Claims. (Cl

The present invention relates in general to a method of and apparatus for burning ash-containing solid fuels, and more specifically, for

burning bituminous and semi-bituminous coals in a relatively coarsely pulverized or crushed condie tion in afurnace of the cyclone type.

Thegeneral object of our invention is the provision of an improved method of and apparatus for burningl fuel of the character described in a vertically arranged furnace f the cyclone type at very high rates of heat release and with a discharge of the gaseous products of combustion from the bottom of the furnace, while maintaining continuous operation' over a wide range of ratings with\a minimum' carryover of unburned fuel and separation and recovery of substantially all of the recoverable ash content of the fuel in a molten condition before the gaseous products of combustion reach the main convection fluid heating surface. A further and more specific object is an improved methodof and provisions for supplying fuel and air to a furnace of the character described. i

. The various features of novelty which characterize the invention are pointed out with particularitydn the claims annexed to and forming a part of this specification. For a better `understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which are illustrated and described several embodiments ofthe invention.

Of the drawings: Fig. 1 is an elevationof a portion of a test cyclone furnace installation constructed and operable in accordance-with this invention;

Fig. 2 is a horizontal section taken on the line 2-2 of Fig. 1; Fig. l3 is an enlarged vertical section taken on the line -33 of- Fig. 2 showing the furnace fuel andv air ports; Fig. 4 is-a sectional elevation taken on the line 4-4 of Fig. 2; Fig. 5 is an enlarged view of a portion of the furnace wall construction shown in Fig. e; Fig. 6 is a 4iiow diagram ofthe steam generating system of wthe installation shown in Figs. 1-5; Fig. 'l is an elevation of a modified fuel feeding 4arrange-- ment; Fig. 8 is a plan view of the fuel distributor of- Fig. '7; Fig. 94s a vertical-section taken on the line 9-9 of Fig. 8; Fig. 10 is a sectional elevation of a modied steam generating unit; Fig. 11 is a vertical section taken onthe line iI'-l| of the tube arrangement; Fig. 14 `is an elevation partly in section of a modified form of fuel and air supply provisions; Fig. 15 is an end view partly in sectionof the construction shown in Fig. 14; Figs. dand 17 are horizontal sections taken on the lines lS--I and i'i-ll of Fig. 14; Fig. 18 is an elevation partly in section of another form ofvfuel and air supply provisions; Fig.- 19 is a side view, partly in section, of the apparatus shown in Fig. 18; Fig. 20 is an enlarged horizontal section taken on the line 2li-20 of Fig. 18; and Fig, 2l

is a horizontal section taken on the line i--l of Fig. 19.

In Figs. 1-6 is illustrated an experimental test cyclone furnace installation constructed in ac` cordance with the invention'and operable for carrying out the .improved method hereinafter described. While various kinds of liquid, gaseous and solid fuels can be burned in the apparatus illustrated, the furnace construction and method' hereinafter described are especially designed and particularly adapted for burning bituminous and semi-bituminous coals having an ash fusion temperature below 2800 F. and reduced by crushing or pulverization to an aggregate or mixture of particle sizes not over 1/2". Solid fuel of this general character has been referred to as granular" or granulated fuel. The fines in the mixture passing through a 200 :mesh screen may be between 3% and 20%, depending upon the volatile content of the coal. The` minimum volatile con'- tent of the coal may vary considerably, ranging, for example, from 20% for a coal having an ash v fusion temperature of 2350 F. to 40% for a coal with an ash fusion temperature of 2700 F. A certain percentage of nes in the mixture is de- Fig. 10; Fig. 12 is a horizontal section taken on" the line l2-I2 of Fig. 11; Fig. 13 is a plan view taken on the line I3--l3 of-Fig. 11 illustrating undesirable as the amount of ash leaving the furnace as iiy ash is proportional. The larger the size of the coal particles, the less the vamount of fly ash, but the `higher the percentage of coarsel particles, the higher the air velocity required to keep the particles in motion in the furnace' until they are deposited on the vslag-covered furnace walls. A consideration of all of the factors involved makes a relatively coarse fuel mixture most A desirable.

For example, a desirable mixture for bituminous' coals having about 11% moisture.

15% ash, 39% yvolatnes'ana a heat value of 10,300 B. t. u. per pound as fired. would be Sii-100% .through a 4-mesh screen, 40-50% through 30- mesh, 10- 18% through 10G-mesh, and 640% through a 20o-mesh screen.' Coal of thecharacv ter described is supplied ata regulable rate from a feeder met shown) connecting a bm or crusher to a supply pipe I0.' the lower end of which opens g donnee the circumferential wall of a subjacent l5 4secondary furnace chamber I9. The inner half i of the tube portions in the boundary walls of the two furnace chambers have metallic studs welded thereon, as shown in Fig. 5, and covered by alayer of suitable high temperature refrac tory 2i, such as plastic chrome ore. A layer of heat insulation 22 is placed between each tibe coil and the casing I2. 1f

The inner exposed surface of the. circumferential wall of the main furnace chamber is made to conform as much as possible' to a uniform circular crosssection throughout its height to avoid interference with the desired helical flow path of i the fuel and air and products of combustion downwardly through thisv chamber. The maindeviation .from^ the desirable uniform circular cross-section is due to the necessary openings for heretofore described. annular pocket 28 open at its upper side only is Ithus formedaround the downwardly flaring gas outlet v2.9 defined by the throat 35. The outer end of the coil '38 is seriallyv connected to the lower end of the tube coil I1,

while the upper end of the throat coil portion has a bare rtube portion 86 "extending downwardly along the inner side. of 'the .throat and connected" to the outlet end of anintlermediate cooling coil 38 arranged in an external water tank 39. l

An intermediate pair of adjacent tube portions in the throat are formed with a pair ci?v angularly spaced 180 bends 4I) to define therebetween a slag discharge opening 4I slightly above the floor level of the pocket'and at the side of the throat remote froml the `secondary furnace gas outlet. The slag outlet is angularlyspaced from the fuel and air inlet slot 23,` and, as shown in Fig. 2, is v preferably located approximately 90 rearwardly.

of the slot 23 relative to the direction of rotation oi the streams in the main furnace chamber.

With this arrangementany slag in a fluid condition on the furnace ,chamber floor will flow.

towards tlfeslag discharge opening and drop therethrough into the `secondary furnace cham- The secondary furnace chamber 'I9 is also of substantially circular cross-sectional area except at the side thereof which opens through a horizontallyelongated rectangular gas outlet opening 43 to a. tunnel 44 formed in the' lower part of thewater tank 39 and surrounded-by the water the entry orfuel `and, air to this chamber and the .construction ofthecircumferential wall portions adjacent the points of fuel and air entry vso as to insure movement of the entering fuel and air in the desired flow path, minimize interference with the streams already in the furnace, and to avoid solidified slag land coke formations on the furnace chamber walls, particularly around the points .of fuel and air entry. As illustrated in Figs; 1, 3 and 4, all of the fuel and airis Dreferably introduced into the furnace chamber through e. plurality vof vertically elongated ports in vertical alignment and extending over a maior portion of the furnace chamber height. The inlet ports are part of a verticallyelongated slot 23 arranged tangentiallyio vthe outer end of a section of an involute curve and extending about one- I6 of the circumferential wall shaped inthe form half the circumference of. the furnace chamber.

The slot is defined lby connecting vertically adjacent pcrtions-pf the tube coll into two radially spacedoverlapping groups of 180 bends 26 and 26, the bends 28 being at the outer end 'ofthe involute curved walli'section I8". The upper end of the slot 23 terminates slightly below lend of the furnace chamber.

The top ,of the main furnace chamber I5 is closed by a substantially circular roof 30 formed by av hat studded tube coil 3| serially connected at its outer end to the tubecoil I1 and its other end connected to a suitable steam and water separating space. The tube coil 8|. is covered on its lower side by refractory material 2l, andrnsu- 5 lated at lits upper side like the tube lcoil I1. A- central opening in the roof- 30 is closed by an access door .82' having a central inspection opening is iluid cooled'by a coiledtube 38 defining a flat annular outer/bottom section 3 .4-and an upwardly converging inner. throat section 35, Ithe upper and.. lower sides of the flat tube portions and the outer and inner sidev of the throat tube portions*beingv the upper' that point therein. The chamber I8 has its bottomd fluid cooled by a flat coil 46 lserially connectedat its outer end to the bottom of the coil I8.. the`upper end of which is connected to the inlet end of the `coil 38. A feedwater'pump or other means establishes a circulation through the other end of the coil 48. The tube coil 46 is studded and covered with a-layer of refractory insulation 41 as heretofore described, except that the refractoryon the bottom tube coil slopes downwardly toward the gas outlet side of the chamber I8. Adjacent circumferential wall tube portions are bent to provide a slag discharge opening at the lower end .of the refractory bottom of the chamber I9. The lower end of ythe gas outlet 43 terminates above the level of theslag discharge opening 50, as shown in Fig. 4. The portions of the tube coil I8 extending across the gas outlet are aranged to form a slag screen 5I at y bending vertically adjacent horizontal tube portions-into vertically spaced aligned tube groups. With this arrangement slag partlcles in suspension in the outgoing furnace gases will be collected by the screen tubes. The heating gases flowing through the tunnel 44 are discharged through a stack connection 53, which 4leads tothe atmosphere inthe experimental installation, but which-would lleadto a point of heat utilization in any commercial installation.

' A slag outlet 55 is locatedin the bottom Lof the stack connection for the4 removal of any slag swept mtpthe tunnel u `from the chamber it.

. 31. The bottom of' the main furnace chamber I6 The water circulating system of the experimental-unit' is diagrammtically shown in Fig. 6.

In this system, the water isv iecl` into the bottom.

coil 48, and .thence through the coil I8' vto the.

external cooling coil to reduce its temperature before enteringgthe throat coil. `The external coolix'fg coil maybe partly by-passed, if desired. The

studded and covered with plasticrefractory as' 15 water flows down through the throat coil and upwardly through the coil I1. 0n 'leaving the roof coil 8 I, the water and any steam generated isdellvered to the expansion tanks where'any makeaesvgaoe 3 up Water required is added. The water is utilized in the air heater for preheating some 'of the air supply and then returned to the pump.

The fuel and air supply provisions comprise a combination hotgas mixing and water heated air .heater 60 having means for discharging two streams of hot air, heated to .different temperatures if desired, through a primary air duct 6l and a secondary air duct 62. The ducts 6l and 62 are connected to compartments 63 and 64 reu spectively, of an air casingl t mounted on the cyclone furnace. The casing 65 has a laterally extending nozzle section 66, the discharge end of which terminates in the furnace slot 23. -The nozzle section 66 'is of relatively narrow width throughout its length, corresponding to the Width of the slot 23 and is divided into three similar vertically elongated horizontally directed ports 58, 69 and 'H0 by horizontal diaphragme 61. `The remaining portion of the casing is constructed so 5B and the compartment 64 only into the ports 69 and l0. Each of the nozzle ports is provided with an adjustable damper, the damper 1l in the port 68 having a curved outer end and being variable from a wide open position to a half closed position, as shown in Fig. 3, by threaded rods l5 passing through nuts welded on the side of the casing, the inner end of each rod having a loose connection with the correspondiung damper to permit the rod to turn. A stationary curved baille 'i4 cooperates With the curved outer end of the damper ll to prevent by-passing of theport area controlled by the damper. 'I'he dampers 'I2 and 'i3 inthe secondary air ports 69 and l0 respectively are flat and hinged at their outer ends so that they are variable over the` full width of the corresponding port without changing the position of the air streams relative to the involute curved circumferential wall section, The dampers 'F2 and 'i3 are adjusted by a single control rod l5, While the damper 'll is controlled by two pairs of vertically spaced control rods to permit a .uniform lateral adjustment of this damper and thus provide a uniform effective flow area throughout the length of the port 68. The secondary air compartment te has an inclined group of curved that the compartment 63 opens only into the port directing vanes i8 positioned therein, as shown in Fig, l, to provide a uniform flow of secondary air throughout the height of the ports B9 and 10. As shown in Figs. 1 and 3, the fuel supply pipe I 0 is connected to the top port 68 through a rectangular opening in the upper part of one side thereof to supply a controlled amount of-fuel to with only a small percentage of 'excess' air over a wide, range of ratings and separation and removal of a high percentage of the a-sh content of the fuel in a molten condition before the gaseous products of combustion leave the furnace. In

carrying out the, improved fuel burning method,k

the furnace is initially preheated by an oil or gas burner temporarily inserted therein. The fueland air suppliesare 'then controlled to provide a mixture of the' fuel particles and primary air which is discharged at a high velocity through the port 62, and a supply of high velocity secondary anfhglxirough one or both of the secondary air ports 69 and 10. The total air supply is directly proportioned to the amount of fuel supplied to thefurnace, the fuelair.ratio .main-f tained being such that the total air supply is not more than about 20%, and preferably less than 15%, in excess of the theoretical combustion air requirements. The air-fuel ratio may be varied 'to some lextent as a lower excess air ratio is usually desirable at the higher fuel rates to increase the adiabaticv furnace temperature and facilitate slag tapping. About one-third of the air supply is delivered to the primary air port. Due to the admission of the fuel from the pipe Il) into lthe upper part of the port GBand the high velocity of the air passing through that port. the discharge therefrom into the furnace will usually consist of an intimate mixture' of fuel and air from thevupper part of the portland substantially clean combustion air from the lower part. V

The entering vertically elongated stream of primary air and fuel is directed horizontally along the involute curved section of the circumferential wall of the furnace chamber and as it moves -therealong is exposed to the high temperature 'rapid combustion of the fuel particles results in an early release of the ash content thereof, and due. tp the centrifugal effect thereon, the ash released. is deposited on the furnace walls, and particularlythe circumferential wall, resulting in the formation of a thin. layer or illm of molten ash or slag, which adheres to the refractory surface of the Walls and quickly vprovides a sticky surface to which fuel particles, particularly the larger fuel particles, in the whirling fuel and air stream, will adhere and be completely hurriedA thereon. 'I'he rate of combustion of the fuel parm ticles held on the furnace walls is substantially increased by the scrubbing action of the contacting air. The use of preheated primary -air is particularly desirable to facilitate the ignition of the entering fuel. With the cyclone furnace constructed andarranged as described itis deemed essential for efficient operation that the primary air-fuel stream should always enter 'the furnace chamber at a point above the level of the se'condary air` admissionport's.

`The secondary air enters 'the furnace through4 the ports 69 and 'F0 in the same angular direction and at a high velocity'of-'the same order as that of the whirling stream of primary air andfuel. The secondary air stream intimately mixes with the stream of burning fuel, air, and products offcombustion andv passes downwardly therewith f in the helical path of flow. Combustion of the remaining 'fuel particles in suspension ap.

preaches completion as the whirling stream reaches thebottom ofthe furnace 'chamber .|5. At this point and due to the location and configuration of the throat 35, the whirling stream is forced to-move inwardly and upwardly to reach the gas outlet through the throat. 'This relatively abrupt axial reversal in direction of movel ment of the stream results in lash or slag par- .'ls any tendency for slag formations to form ad l jacent the point ofentry. Any such 'formations I eration anyslug ticlesin suspension being thrown out of the whfirling'- stream and' vdepositedv on the furnace bottom around the` throat. Any incomplely burned fuel particles will separate out of the gas' stream in this flow reversing zone due tothe gravity and inertia effects thereon andwill remain in the annular pocket 2B, either partly em? bedded Ain the slag surface therein or moved around inthe pocket by the whirling gases therein', until all -of the-combustible .content vis consumed and-the ash content released. The llocation of the slag outlet ll Vinthe throat above ltheA bottom of the 'pocket insures a slag layer therein under all operating conditions. The slag coating on the furnaeewalls rapidly reaches an .equilibrium thickness, which is dependent upon /the relative values of the furnace wall temper ature, the ash fusion temperature, the mean furnace chamber temperature, and the velocity of the contacting gas stream. The deposition of additional 'slag results in a flow of slag down the Jfurnace walls to the furnace chamber floor. .The molten slag accumulating on the furnace floor overflows through the slag discharge opening-4l into the secondary furnace chamber I9, where it flows down'to the floor thereof to the slag out-- let 50. The. furnace gases flow downwardly through the gas outlet'29 into` the secondary furnace chamber, turn therein and flow through the outlet 43 and tunnel 44 to the stack connection BJ. At high capacity operationthe high gas velocities present caused a substantial` amount of slag to be swept out of the secondary.

furnace into the tunnel 44 in which it flowed to the slag outlet 55. When the gas velocity through 4the outlet 3 was reduced to'a value equivalent te woohoo B. t. u. per sq. rt. of area, suman-a tially all of the slag could be tapped Afrom the slag outlet 50 in the secondary furnace.l

The relative arrangement vof the primary airfue'l andsecondary air ports described is particularlyadvantageous in lminimizing slag forma tions on the circumferential wall at points where they would interfere with the entry of either the fuel orair. Slag depositing in any nozzle port would 'cause lan increase in the flow resistance therein and correspondingly reduce the fuel orformatlons in this area, and particularly at. the trailing edge of the fuel port.

The relative proportions of the furnace parte. and particularly of the height of the main furl nace chamber, height and diameter of the throat. 'and dimensions of the fuel and air 7inlet porta relative to the furnace chamber diameter, play an important part in the operating characterla tics of a furnace of this type. as described and Y claimed in the copending application of applicants and Ervin G. Bailey, Serial No. 382,262,

illed March '1, 1941, I.

By way of example, and not of limitation, one test run of the lexperimental installation illus-x trated in Figs. l-6, gave the following values which indicate representativesconditions to be maintained in accordance with the present invention. The fuel burned was Ohio No. 8 coal reduced to the following sizing:

The ash as anahlzecl` showed an initial deformation temperature of 2l20 F., a softening temperature of 2210512., and a fluid temperature of 243?. F. The coal was redv at a rate of 2280 lbs. per

40, hr. with anf excess air of 19.5%. The total air supplied was 25,700 lbs. per hr., of which 26.85% was supplied as primary air, and 73.15% as sec ondary airthrough both of the ,secondary air ports. The air velocity through the primary air,

' port was 21,000 ft. per minute and through the secondary air ports 22,000 ft.per minute. The

" average velocity of the gases passing out through airl supply therethrough. Such accumulations" would also tendto disrupt the air and fuel flow -path inthe 'furnace and to destroy the desired whirling of the stream along thefurnace chain:

ber circumferential wau. with the al1-and fuel stream `entering the furnace chamber taugentially to an involute curvedwall section.eirtendefi55 ing'a substantial distance, the entering streams have an opportunity to gradually merge with Vthe whirling furnace gases before intimate con-'- tact with the' descendingv slag. .Only the {seo ondary air ports are in a position wherelnthere can be quickly removed' without' shutting down the furnace by momentarily reducing or shutting of! the secondary air supply through the nozzle -port affected, and Supplying all .the seabndary air through the other nozzleport. .Withthis op- -f'accumulatlons atorv adjacent the level of thev closed 'port willbe quickly melted and mus eliminated. 'The reialv'e'vesmon or ythe refractory faced roof of the :chamber .mately the maximum length attainable 'in such a furnace. It has been ,found that improved operthe throat 35 was calculated as- 30,350 ft. per minute. The air was supplied at a temperature of 390 F.. and the furnace temperature was approximately 3200 F. The heat releasef was 1,087,000 B. t. u. per cu. ft. of furnace volume.

.About 93%' of the recoverable ash content of the fuel was removed as molten slag and found to be prcucany free or combustible matter.-

or. slag formations faroundlthe furnace chamber inlets. a continuous flow of slag throughthe slag :Opening 4l cndnons in the* fumacechamaetg.

'with the @struction illustrated in rigs. 1 6

operating 'as' described, the lengthl of the helical path of travel of' theiuel and gir downwardly chamber'will beubstam,

tnr'oughfthe, rurngce tially the s'ame atlall'ratlngsand be approxiating conditions over a wide'range of ratings I5 and the fuel inlet port insures a high furnace'I4 temperature inthe fuel entrance ione lof the furnace chamber and` thereby the absence of coke canjbe obtained if' the point of fuel' entry; and thereby the length of travel in the furnace chamberbefore, reaching the gas outlet, is'y'aried with' lthe rating, and particularly by lowering the point 'of fuel entry as the rate of fuel firing decreases.

' For the best results with such operation. substantially .of the vsecondary air supplied should be Good operating conditions may be defined as those resulting i'nl6% 1,17% CO: with no coke t l admitted Ibelowthe level of the 'fuel entry point.

in Figs. 7-9 a modified arrangement: of fuelsupply means'is illustrated in which fuell can be. supplied to any one or combination of ports. In-

the modified construction a threeway distributor 80 in the fuel supplypipe l0 permits the fuel.

to be divided between three separate pipes 8 ,"82,.

of each port is controllable by a hinged flat dampe'r 86 similar to the dampers-12, 13 shown in Figs.

2 and 3, and capable of independent adjustment toclose off the air supply through any port. Good operation has been attained at the higher fuel ratings with fuel and air passed through all of the ports, or only the top port with air alone through the middle and bottom ports; at intermediate ratings with fuel land air discharged both of the remaining ports. The effective width through the top and middle ports 00 andg, or

the middle port alone, and secondary air through the' bottom port 10, and at low ratings with all of .the fuel and air through the bottom port "l and the top and rniddle ports closed oli. It is highly desirable in any case where fuel is supplied through only the middle or bottom portsI I' 'that no air be supplied through any higher port. -In 4one test run in which all of the air and coal of the character described were passed through the bottom port and the top and middle ports completely blocked 0R, the coal was fed at a rate of .480 lbs. per hr. with 20.69% excess air. The total supply of'air. at 5550. lbs. per hour was sup-1 plied to the bottom port at a velocity therethrough of 10,000 ft. per minute, and a temperature of 376 F. y The furnace temperatureby opt0 and Si. s Y drum 94. The slag screentubes separate the ticalpyrometer was 2855- F., and the heat release rate 226,800'B. t.'u. 4per cu, ft. per furnace volume. The slag iwed `freely to the 'secondary furnace chamber. andv operating conditions were good.- The y ash amounted to 1.2% of the 'fuel witha'carboncontent of. .75%.

In Figs. -13 we have illustrated a natural circulation stationary steam generator unit .modifled for firing by a, plurality of cyclone furnaces 90 of the general'construction illustrated in Figs'. 1-6. .The generating unit is .of the Babcock 8i Wilcox type, comprising horizontally inclined steam generating tube banks 0| and 92 with an interdeck superheatei` 93. 'Ihe tube banks discharge through end headers and circulating tubes into a steam and water drum 9d from which steam is delivered to the superhe'ater. lIBelow the tube banks is arranged a row of alternately 'bent slag screen tubes 05 extendingbetween headers The header 9i lis connected to the main banks of generating tubes from a fluid cooled' furnace chamber for th'e cyclones. The

chamber 98 has a lateral .extension 90 into which.

the cyclonefurnaces M disharge. The roof of the furnace extension 99 is defined by arow of water tubes |00 extending `from the header 9E. downwardly along the furnace wall and laterallyv `to a header |09, portions of the tubes '|00 being bent. to clear the throat of 'each cyclone furnace.

" ber A80.

A row ofinlined block-covered .water tubes |02 forms an inclined floor.' for the furnace extension 99 tocause slag depositing thereon to flow down--v wardlyinto the ash pit |03 of the furnace cham- As shown in Figs. 111-13, the circumferential wall of each vcyclone furnace chamber is fiuid' cooled by a circular row of vertically. extending water tubes |05 connected, at their upperand lower ends to annular headers |06 and |01 respectively. The cyclone furnace cooling.tubes arerconnected into 'the circulation system of thel boiler by tubes |08 connecting the header |06 to the slag screen header 96 and by a downcomer connection |09 to the header |07. A separate cooling fluid circuit is used for the furnace throat gentially arranged to the outer end of an involute curved portion of the furnace circumferential wall and a slag Voutlet H5 is formed in the side of each throat adjacent the furnace chamber floor level.

:With this construction and arrangement of the parts reduced fuel may be burned at high rates -of heat release 'in each cyclone furnace, as here, tofore described, .with the heating gases generated passing out `through the bottom'throat and thence laterally through the furnace chamber extension S9 and upwardly'through the furnace ating tube banks. The slag separated in each.

chamber 08 into contact with the steam genercyclone furnace .deposits on the circumferential wall thereof, and flows downwardly to the slag discharge opening liti from which it drops'onto the floor tubes 02, and is discharged therefrom into the ash p it |03. The construction illustrated in Figs. 10-13 shows an advantageous arrangement; of cyclone furnaces for use with an .existing steam boiler.

negligible amount `of ash in suspension in the In view of the relatively gases flowing -up/wardly through the furnace chamber 08, the sizeof this chamber can be reduced for a `completely new installation.

In the modifications illustrated in Figs. 14-21, the point of 'admission of the fuel and combustion air supplied can be varied relative to the furnace chamber height asl desired, thus per'- rnitting regulation of the length of travel of the enteringfuel and air in the furnace chamber in accordance with changes in fuel rating, or any other varying voperiatting condition.

In the modification illustrated in Figs. 14-17,

. the points of entryv of the fuel and air into the furnace chamber are simultaneously controlled with the same relative positions of the entering fueland air streams maintained throughout the range of adjustment. For this purpose the air duct-nozzle section 06y has a vertically inclined open ended stationary tube |20 mounted thereon and within which is concentrically positioned a I stationary fuel pipe 52| connected at its upper end to the fuel supply pipe l0. The pipes 20,

throughout their length and terminate at a flanged opening |22 in the top of the duct section pipe |2| consisting of` an open ended pipe |23 surrounding the pipe |2| and` provided with a pair of lateral guide wings |24 which flt into vertically inclined guide slots |25 in opposite sides of the duct section 66. The tube |20 is also formed with similar guide slots .|26 which are continuations of the slots |25. The pipe |23Qhas afpair I of adjusting rods |21 on its wings .|24 whichextends upwardly in the slots |28 and are held in any desired vertical position relative to the tube have an annular space therebetween.

- i |20' by a sleeve and set screw |23. The direction 1005.35 of the recoverable ash in the coali of-air'tra'vel in the duct section 6B is indicated by the arrows in Figs. 14 and 17, and the pipe |23 is so inclined The lower end of the pipe |23 has a reduced extension |20 for receiving various types offuel4 tipsrfThe tip |30 illustrated has been found particularly eifeetive in operation in securing a distribution ofthedescendingfuel particles overa substantial part of the height of the duct section l Il and consists of a sleeve |3| fitting over the pipe extension |20 and a downwardly tapering that its lower end leads its upper end relative to the direction of air travel.-

flue gas analyses averaged 11.31% C01, t I 'and 0% CO. Operating conditions during and at the end of the testirun were good, land the only accumulation in the furnace chamber'was athin layer of slag onl the furnace walls.i l

11n the modied Aburner assembly illustrated inFigs. 18-21, the point; of entry of the fuel stream'into the duct section ,85, and consequently the furnace chamber, and the eiective height tongue |32 formed by cutting away all but a narrow sector of the sleeve wall at the outer side thereof.

xWith the construction described, the stream o fuel particles flow down through the pipes i and |2| into the pipe |23. The amount of fuel suppliedis normally not suicient to iill the entire cross-section of these pipes and the fuel stream.

tends to concentrate along the side of the pipe 'ne facing' the incoming nigh velocity air stream. The descending fuel stream tends to continue down along the concave face of the tongue |32 ysubject to the action 'of the air stream sweeping around the sides of and below the tongue. pipe |23 and attached wings |24 act as a damper The for the air duct section 63, concentrating the air flow therethrough to the portion of .thel duct b e.

low t e wing level. The. pipe |23 is shown'in its low ost-position, which would normally be used for the lowestgrating for which thefurnace is designed; As the pipe |23 is`raised,such as fcrhlgher fuel ratings, 'a greater percentage of the air will pass below the tongue |23. As compared to the portion of the air stream passing of the air stream in the duct are separately variable. In this arrangement the -fuel pipe y|0 has a vertical extension |40 vpositioned in a rectangular casing |4|,' mounted alongside and' extending above the air ducts'ection 06. A movable burner pipe. |42 is alsopositioned`v inthe lower part of the casing |4| inv telescoping rel'a' tion with the lower end 4of the pipe |40. AThe I lower end ofthe pipe |42 extends downwardly and laterally, as indicated at |43.' andcarries a' vertical guide plate |44 around its discharge end.

Y The guide plate |44 is positioned 'in vertical'slots Y mounted lin guide slots inthe sides 'of the duct around and immediately below the vispngueand acting as primary air, the remaining portion of the air stream will be relatively clear and of the nature of secondary air. v

' while 'the iuei bumey/eenstruenien ,illustratedin Figs. 14-17 isladapted for use in various types of furnaces, it is particularly adapted for use .with a cyclone furnace constructed and arranged as.

illustrated in Figs. l-IS.m In one 24-hour test run of a cyclone furnace with such a fuel burner assembly, the fuel burned was Kincaid coal having the following proximate analysis:

' terminating slightly above statutes we have' illustrates and described herein the best forms of .the now known to us.

l"rire ssh u analysed med an initial :remi-im.;-

uonymnpersturs er im# r., a'eei'tening temof 2,060' F.. and a fluid temperature of 2200??. 'lhecoal wasiiredat iba/haxusing 0.3% excess air. The air velocity through thebu'rnen was 18,300 ftJmin., and

through the thoat'32,100 ftJmin., the'air tern--v being 44s' F. 'rae perature'at the furnace inlet ash reoovered'through tbe/ slag holes in the sfeechamber and tunnel amounted therateof 2448.-

u! stream ciau' |45 inthe side of the duct 60. The fuelpipe |42 l can be raised and lowered'relative tothe duct 60 by the hand wheel |41 operating through a pinion gear |48 and a rack |49kon the side of the pipe.

With this arrangement the position of th'eyfuel pipe can be vertically adjusted inthe casing |4| `tovary the position of its discharge end |43 rela-l tive to the duct section 86, 'through which a stream of high velocity air is'passed inthe direction indicated bythe arrow .in Fig. 21. effectiveheight of the air streamin the duct section 88 is controlled byea .vertical damper' |50 sectionfi immediately in advance ofthe point of fuel entry. The position of the damper is ver tically adjusted by meansv of 'a rod- |5| on its 'upper end. The damper and rod are held in any desired position by a sleeve |53, mounted on the rod at the upper end of a vertical extension |54 of the damper guide slots, and a set screw |55.

With this arrangement the discharge end of, the fuel pipe |43 is adjusted to the proper position for' the corresponding fuel rating, and the damper |50 is correspondingly adjusted Aso'thai'. it is normally in a position fwith its lower end; the upper end of the fuel, outlet, as indicated in Fig. 18. `The stream of high velocity air sweeping. through theA duct 06 below the damper |50 picks up the fuel par' ticles -discharged through thelower end of the fuel pipe and discharges thea/1 into the ,furnace chamber.' As in the burner assembly illustrated in Figs. i4-17,'the upper portion of the air stream Awill act as primary'air'. while the lower portion willbe inedect secondary While in accordance withthe provisions ofthe those skilled in theart. will'understand that changes hay be madeinthemethod and forni of the apparatus discloses rivi'uinjut departing l:mi

the spirit ofthe invention covered by-our claims.; and that certain features of the invention may,

sometimes be used to advantage without-acorta;

spending use of otherifeatiuos.

.Weclairm g i. -The process 'of burning-a slew-forming fuel 'at highrajtes 'of ina Ycyclone type s verneem ed. f :aguacate-1 duced ciuiditiiiu.iilifV cal path along the circumferentialv wall of suifly cient length to cause the release of the ash ccntent of the fuel and the deposition of slag on the circumferential wall to form a sticky surface thereon sufficient to cause fuel particles to adhere thereto, and withdrawing ash separated in the furnace chamber. in a molten condition at the bottom thereof.-

2. The process of burning a slag-forming fuel at highvrates of heat release in a cyclone type furnace having a substantially cylindrical furnace chamber with a gas outlet in its bottom which'comprises -introducing the fuel in a re duced condition in suspension in a high velocity stream of air directly into the upper part ofthe furnace chamber and vtangentially to the circumferential wall thereof and in a horizontal direc tion while maintaining a normal mean temperature in the furnace chamber above the fuel ash fusion temperature, introducing the remaining air for combustion in a high Velocity stream tangentially to the circumferential wall at a position between the point of fuel entry and the gas outlet and horizontally in the same angular direction as the fuel stream, causing the fuel and air so introduced to move downwardly through the chamber to the gas outlet in a helical path along the circumferential wall of suiiicient length to cause the release of the ash content of the fuel and the deposition-of. slag on the circumferential wall to form a sticky surface thereon sufficient to cause fuel particles to adhere thereto, and withdrawing ash/"separated in the furnace chamber in a molten condition through the bottom thereof.

3; The process of burning a slag-forming fuel at high rates of heat release in a vertically arranged furnace chamber of substantially circular horizontal cross-section having a gas outlet in its bottom which comprises introducing the fuel in a reduced condition in suspension in a high velocity stream of preheated air directly into the upper partof the furnace chamber tangentially to the circumferential wall thereof, maintaining a normalmean temperature in the furnace chamber above the fuel ash fusion temperature, introducing alrffor combustion in a high velocity stream tangentially to the circumferential wall at a position'between the point of fuel entry and the gasgoutlet and in the same angularl direction as the fuel stream, causing the fuel and air so.-

introduced to move downwardly through the chamber in a helical path along the circumferential wall of suicient length to cause the release of the ash content of the f uel and the deposition of a layer of slag on the circumferential wall sufficient to cause fuel particles to adhere thereto, causing the descending gas streams tobe deflected at the lower end. of the furnace chamber i inwardly and upwardly before vreaching the gas outlet. and withdrawing ash separated-in the furnace chamber in a molten condition through the bottom thereof. f,

4. The process of burning a slag-forming fuel at high rates of heat release in a vertically arbetween the point of fuel entry and the gas outranged substantially cylindrical furnace chamber havinga gas outlet in its bottom which comprises introducing the fuel in a reduced condition in suspension in a. high velocity stream of air dil rectly into the upper partl of 'the' furnace chamvber tangentially to an involute curved portion of the circumferential wall thereof, maintaining a normal mean temperature in the -furnace chamber. above the fuel ash fusion temperature, introducing the remaining air -for combustion in a h'gh velocity stream tangentially to the involute curved circumferential wall portion at a position let and in the same angular direction as thefuel .stl-earn', causing the fuel and air so introduced to move downwardly throught-.he chamber to the introducing the fuel in a reduced condition in gas outlet in a helical path along the circumfer ential wall of suicient length to cause the release cf the ash content of the fuel vand the deposition of a layer of slag on the circumferential wall` sufficient 'to cause fuel particles to adhere thereto,

and withdrawing ash separatedin the furnace.-

chamber in a molten condition through the bottom thereof.

5. The process of burning a slag forming fuel at high rates cf heat release in a vertically arrar: gedl substantially cylindrical furnace chamber having a gas outlet in its bottom which comprises suspension in a high velocity stream of preheated air directly into the upper part of thev furnace chamberv tangentially to an involute curved portion of the circumferential wall therefof, maintaining a normal 'meantemperature in the furnace chamber abovethe fuel ash fusionv temperature. introducing the remaining air for combustion in a high velocity stream tangentially to the involute curved circumferential wall portion at a position between the pointof fuel entry and the gas outlet in the same angular direc-u tion as; the fuel stream, causing the-fuel and air so introduced to move downwardly through the its bcttom which comprises introducing all ofY chamber in a helical path along the circumferential wall of suflicient length to cause the release of the ash content of the fuel and the deposition cf a layer of slag on the circumferential wall sufficient to ca use fuel particles tc adhere thereto. causing the descending streams to be deflected at the lower end of the furnace chamber inwardly and upwardly before reaching, the gas outzet, and withdrawingash separated in the i furnace chambe in a molten condition through the bottom thereof.

6. The process of burning bituminous and semi bituminous coals at high rates of heat release in a vertically arranged substantially cylin dricalfurnace chamber having a gas outlet in the fuel in a reduced condition in suspension in a high velocity stream of preheated air directly into the upper part of the furnace chambertangentially to'an involute curved portion of the circumferential wall thereof and in a hogrizon-v tal direction while maintaining la normafmean temperature in the furnace above the fuel ash fusion temperature, introducing the remainingair for combustionat a high velocity tangentially to the involute' curved circumferential wall por-V tir-n at a position between the pointof fuel entry and the ges outlet and horizontally in the same angular direction as the fuel stream, causing the streams of fuel and air so introduced to move downwardly through the chamber in.. a

helical path along the circumferential wall 'ofiL sufcient length to cause the release of the ash `content ofthe fuel and the deposition of a layer Y 7. Apparatus of slag on the circumferential wall in condition Ato have fuel particles adhere thereto.causingthe descending streams to be deflected at the lower end of the furnace-chamber inwardly and upwardly' before reaching the gas outlet, and withdrawing ash separated in the'furnace chamber in aV molten condition through the bottom thereoi.v t

for. burning a slagforming fuel which comprises a furnace chamber of substantially circular cross-section arranged with its axis 'l substantially vertical and defined by walls having aninner exposed refractorysurface and wall cooling tubes proportioned for the maintenance of'said refractory surface under a normal mean fuel ash fusion temperature, vmeans for introducing a high velocity stream of air and slag-forming fuel in suspension `into the upper part of said furnace chamber including a fuel port in and arranged tangentially to the circumferential Wall of said chamber, -a bottom for said furnace chamber having a gas outlet therein, and a vertically elongated air port arranged tangentially to s'aid vcircumferential wall at a. location bel tween the fuel poi-tand said gas outlet.

8. Apparatus for burning a slag-forming fuel which comprises a substantially cylindrical furnace chamber arranged with itsiaxis substantially vertical' and defined by walls havingan inner exposed refractory surface and wall cooling tubes proportioned for the maintenance of said. refractory surfaceunde'r a normal mean ltemperature in said furnacechamber above the fuel ash fusion temperature,` means for introducing a-'highl velocity stream of air and slag- Aforming fuel in suspension into `the upper part of said furnace chamber including a narrowver- Vtically elongated fuel lport arranged tangcntially to the 'circumferentialwall of said chamber, a bottom lfor said furnace chamber having a vgas outlet therein, a narrow vertically elongated air port arranged tangentially to said circumferen- "tial wall at a location betweenthe fuel' port and said gas outlet and in vertical alignmentf with said fuel port, anda slag outlet-inl said furnace 9. Apparatus for burning a, slag-forming fuel which comprises a substantially cylindrical furnace chambeharranged with its axis substantially vertical and exposed refractory surface and wall cooling tubes proportioned for the maintenance of said refractory surface undera normal'mean temperature in said furnace chamber above the fuel ash fusion temperature, means for introducing a high velocity stream' ofv air .and -'slag-forming fuel'. in

suspension into the upper vriart of said furnace chamber including a fuelport arrangedtangentially to one end of an involute curved portion of the circumferential wallof said chamber, a bill!- tom for' said furnacechamber having-fa gas out'- let therein. an airpo'rt arranged tangentially to vone end of saidinvolute .curved portion ofA said circumferential wall at a' location between the temperature in. said furnace chamber above the' fuel ash vfusion temperature, means for introtemprature in said furnacechamber abovev the ber bottom.l i

11. Apparatus for burning a'slag-forming fuel -which comprises a substantially cylindrical furnace chamber arranged with its axis substantially vertical and defined by walls having an inner exposed refractory surface and wall cooling tubes, means for introducing a high velocity stream' of air and slag-forming fuel in suspension which comprises a substantially cylindrical furlinto theupper'part of said furnace chamber including a narrow, vertically elongated fuel port arranged tangentially to t e circumferential wall of said chamber, a fluid cooled bottom for said furnace chamber'having a central upwardly projecting fluid cooled throaforming a gas outlet,

a narrow vertically elongated air port arranged tangentially to said circumferential wallat a location between the fuel port and said gas outlet and in vertical alignment with said fuel port, control dampers in said fuel and air ports, and a slag outlet in one side of said throat adjacent the furnace chamber bottom.

12. Apparatus for burning a slag-forming fuel nace chamber arranged with its axis substantially vertical andjdefined by walls having an inner exposed refractory surface and wall cooling vtubes proportioned for the maintenance of said refractory surface under a normal mean Atemperature insaid furnace chamber above the fuel ash fusion-temperaturef means'for introducing a high -velocity stream of air and slagforming fuel in suspension into the upper part of said furnace chamber including a narrow vertically elongated fuel port arranged tangentially to one end of an involute' curved Portion of the defined by walls ,having 'an inner circumferential wall of said chamber, a fluid cooled bottom for said furnace chamber having a central upwardly projecting fluid cooled throat forming a-gas outlet flaring towardsits lower end, a narrow vertically elongated airport arranged tangentially to one end of an in'volute curved portion of said circumferential wall at a location between the fuel' port and said gas outlet and in substantial vertical alignment with said fuel port, control dampers in said fuel and air ports, and a slag outlet in one side of said `throat adjacent the furnace chamber bottom.

13. Apparatus for burning a slag-formingV fuel.

` which comprises a substantially cylindrical furnace chamber arranged with its axis substantially fuel port andsaid gas outlet,` and a slag outlet in said-furnace chamberbottom. f f

10. Apparatus -for burning a slag-forming '1121 which comprises 'a substantially cylindrical furnace chamber arranged with its axis substanftially vertical and defined vby walls having an inner exposedjrefractorysurface and L'wall cooling tubes proportioned for .the maintenanaof vertical and defined by walls' having an inner exposed refractory surfaoe and wall cooling tubes, means for burning a slag-forming fuel in suspensionr in. said furnace chamberf while moving downwardly` through a helical flow path along the circumferential wall of saidffurnaceA chamber including a vertically elongated inlet arranged tangentially to the circumferential wall of said cham'- ber, said furnace chamber having a central gasr outlet at one ,end thereof, means for supplying vsaid 'refractory surface undera normal m n 15 fuel to said `inlet at points differently spaced for burning a slag-forming fuel remaining combustion gentially to the circumferential wall of the com- "the position;

with a decrease inthe amount of fuel relative to said gas the lower end of said furnace chamber.-

14. Apparatus for which'comprises a substantially cylindrical furnace chamber arranged with its axis substantially an innerfex-l Vfurnace chamber having a central upwardly projecting throat forming a gas outlet, means for supplying fuel and combustion air to all of said ports, acontrol damper in each of said fuel and air ports, and` a slag outlet at the furnace chamber bottom.

. 15. A steam generatingunit having a furnace lchamber-having a lateral extension, a bank of steam generating tubes receiving heating gases from said furnace chamber, a cyclone furnace havinga gas outlet in its bottom opening into said furnace chamber lateral extension, means in said cyclone furnace at a normal mean temperature above the fuel ash fusion through a helical now path downwardly. along .thecircumferential wall of said cyclone furnace chamber, an inclined which vcomprises introducing" a high4 velocityy stream of air'and fuelin suspension into the upper part of the combustion chamber so as to whirl about .a vertical" axis andmove downwardly along the circumferential wall thereof while burning the fuel 'tomaintain anormal mean temperature in the chamber above the fuel ash fusion temperature, introducing substantially all of the air at a high velocity tanbustion chamber at a positionlbelowthe'position o f fuel entry and in the same angular direction as the whirling stream of fuel and air, causing the fuel land air streams s o introduced to merge and.

move downwardly lin the combustion chamber towards vthe bottom thereof path along the vc :ircumferential wall of. sumcient length to cause substantially vcomplete combustion of the fuel and the release of fuel ash therein in a conditioxrto form a circumferential wall to which fuel particles will ash in-a molten condition from the the combustion chamber.

outlet, and a Slag outlet atA temperature while passingn through a helical l sticky surface on the burning a slag-forming fuel.

introduced into the combustion chamber, wherebya normal mean temperature above the fuel ash fusion temperature is maintained adjacent .the slag outlet.

18. The process of burning a slag-forming solid fuel in a reduced condition in a vertically arranged combustion chamber of substantially circular` cross-section with a slag outlet at the bottomthereof, which comprises introducing the by a normal mean fusion temperature .is maintained adjacent the floor in said furnacechamvber lateralextension arranged to receive molten maintaining.- the said relative positions on air streams, whereby a norfuel -in suspension in a stream of 4air into the combustion chamber at a position tangentially to the circumferential wail thereof, introducing a stream of .combustion air into the combustion chamber at a position tangentially to the circumferential wall thereofA and below the point of fuel entry, and vertically adjusting the point of fuel entry in accordance with variations in the amount of fuel burned in the combustion chamber, wheretemperature above the fuel ash slag outlet.-

19. The process of burning a slag-forming solid fuel in a reduced condition in a vertically arranged combustion chamber of substantially circular cross-section with a slag outlet at the botintroducing the in a high velocity stream of air chamber at a position tan g'entially to the circumferential wall thereof, introducing a high velocity stream of combustion air into the combustion chamber at a position tangentiallyto the circumferential wall thereof and below the point of fuel entry, and vertically adjusting the entry in accordancewith variations in the amount of fuel burned in the combustion chamber while fuel .and combus mal mean temperature above the fuel ash fusion lett temperature is maintained `adjacent the slag out- 20.I The process of burninga slag-forming solid fuel in a reduced condition in a combustion chamber of substantially slag outlet at one end'thereof, which comprises I introducing .the f uel in suspension in a stream of air intovthe combustion chamber at a position tangential to the circumferential wall thereof and axially spaced from theslag outlet. and shifting axially nearer to the in the amount of fuel the position of fuel entry' slag outlet with a decrease f' introduced into the combustionchamber.

21. The process of burning asias-forming solid fuel in a reduced condition in a combustion chamber of substantially .circular cross-section with a slag outlet at one end thereof, which comprises introducing the fuel in suspension in a stream vof air into the combustion chamber at a'position ,.60 adhere and be burned, andwithdrawing separated lower part of 17.' The process of burning a slag-forming'solid 65v to the slag outlet witha decrease in the amount I c fuel in a. reduced condition in a. vertically arranged of substantially circular'l combustion chamber cross-section with a slag outlet at the. bottom thereof, which comprisesintroducing the fuelin owbrdsnoe tangential to the circumferential wall thereof, introducing ostream ofcombustion air into the combustion chamber at a position tangential to the circumferential wall `thereof and between the position .of fuel 4entry and thel slag outlet, and shifting the position of fuel entry axially nearer of fuel introduced into the combustion chamber while Vmaintaining a stream of combustion sir entering tangentially entry and the slag outlet` HOWARD J. KERR.

' JAMES FLETCHER. GEORGE A, WATTS.

T KOOIBTRA- points of fuel and combustion 'airv of the circular cross-section with a' between the position of fuel. 

